1. Field of the Invention
The present invention pertains to dishwashing machine control programs and, more particularly, to dishwashing machine control programs which reduce water and energy consumption.
2. Description of the Related Art
As concerns regarding dishwashing machine energy consumption have developed, several methods have been proposed to limit or reduce the amount of energy and water necessary to perform the series of cycles required for each load of dishes.
U.S. Pat. Nos. 4,559,959 and 4,673,441 disclose one method of reducing water and energy usage wherein a pre-wash is performed. A series of sensors are provided which determine when an amount of soil has been filtered from the wash water, and the wash water is drained from the tub. By having pre-wash cycles in accordance with the sensed amount of soil collected, only the necessary number of pre-wash cycles are performed, and water and energy are conserved. There is no discussion of the desirability of partially draining the dishwasher tub, or of retaining a portion of the water from one wash cycle for use in a subsequent wash cycle.
U.S. Pat. No. 4,289,543 discloses a method for pre-conditioning a dishwashing machine wherein water introduced into the dishwashing machine tub, heated to an effective temperature, and sprayed throughout the tub to condition the food ware items for effective food removal and to pre-heat the tub. Washing and rinsing take place after the conditioning water is drained and fresh wash water is introduced.
U.S. Pat. No. 3,020,917 discloses a dishwasher wherein separate systems are provided for the rinse and wash cycles. The used wash water is retained for use in a subsequent wash cycle.
U.S. Pat. Nos. 4,872,466 and 4,810,306 disclose commercial dishwasher in which a portion of the wash water is drained between wash cycles. The commercial dishwashers described in the '466 and '306 patents have short wash cycles (i.e., three to four minutes) and use a single batch of water for washing and rinsing a rack of dishes. Fresh rinse water is combined with used wash water for subsequent racks of dishes.